Is there any way to combine/simplify interpolation curves?
An fcurve that you see in the graph editor is able to animate only one value throughout an animation. As you follow the curve from left to right, it's x,y location gets translated to the frame and value for the property being animated.

For an object (or armature bone...) you can have one fcurve for the x-location, another for the y-location, one for x-scale and so on, meaning up to nine curves for the loc/rot/scale. You may also have extra fcurves for an object if you have other properties animated, like visibility, shape keys, modifiers, constraints...

While you need an fcurve for each value that you want to animate, you don't have to have an fcurve for every possible value, you only need an fcurve for each property you want to control during an animation. When you insert a keyframe using I->Location blender will create three fcurves for the location. You can also  RMB on the x-location display and choose Insert Single Keyframe to only create one fcurve. If you then use I->Available only the values with existing fcurves will get new keyframes.



If you have excess fcurves that you don't want, you can delete single fcurves in the graph editor. With the fcurve name selected and the mouse over the list press X to delete the entire fcurve.

When you have multiple fcurves, you can also simplify the graph editor display to make it easier to work with. For each fcurve and each group of curves, there is a small eye icon that can show/hide the fcurve or groups of fcurves. The cursor in the header allows only selected items to be listed in the graph editor, while the magnifying glass to it's right allows you to filter by name.